本文關(guān)鍵詞： 自生鈉長石 陡山沱組 磷塊巖 微生物　出處：《地學(xué)前緣》2017年01期 　論文類型：期刊論文

【摘要】：文中報(bào)道了在華南新元古代震旦紀(jì)陡山沱組磷塊巖中首次發(fā)現(xiàn)的大量微米級自形長石。巖相學(xué)觀察顯示這些長石為自形-半自形板-柱狀,呈團(tuán)聚狀或分散狀產(chǎn)于砂級膠磷礦顆粒中,粒徑大多在10~30μm,光學(xué)顯微鏡下無法觀察到雙晶。掃描電鏡能譜(EDS)半定量分析表明這些自形長石為鈉長石。電子探針(EPMA)分析顯示所測樣品鈉長石端員(Ab)平均含量為97.96%,與典型自生鈉長石成分一致。鈉長石所包裹有機(jī)質(zhì)的拉曼光譜特征指示其經(jīng)歷的最高溫度不超過350℃,排除了其來源于高溫的巖漿巖或高級變質(zhì)巖的可能性。以上資料表明這些微米級自形長石為典型的自生成因高純鈉長石,可能形成于磷塊巖的早期成巖階段。自生鈉長石與絲狀化石常相伴出現(xiàn),與前人通過嗜堿菌還原黏土礦物實(shí)驗(yàn)所獲得微米級長石及微生物的產(chǎn)出關(guān)系相似;鈉長石核部可見富含有機(jī)質(zhì),表明后者可能促進(jìn)了礦物的生長。文中提出磷塊巖中自生鈉長石的成因模式:鈉長石的Al和Si來自于黏土礦物的分解,該過程可能受嗜堿微生物介導(dǎo);Al和Si與來源于海水或碳氟磷灰石晶格中的Na~+結(jié)合,在低溫條件下結(jié)晶形成高純度鈉長石。微生物及其相關(guān)有機(jī)分子可能為鈉長石結(jié)晶提供了成核點(diǎn)。
[Abstract]:In this paper, a large number of micron automorphic feldspar were first found in the Phosphorite of the Neoproterozoic Doushantuo formation in South China. It is agglomerated or dispersed in sand grade cemented phosphate rock particles, the particle size of which is mostly 10 ~ 30 渭 m. Double crystals could not be observed under optical microscope. The semi-quantitative analysis of scanning electron microscope (SEM) EDS showed that the eutectic feldspar was albite. The electron probe analysis (EPMA) showed that the measured sample was albite end member Ab). The average content was 97.96%. It is consistent with the composition of typical authigenic albite. The Raman spectra of the organic matter encapsulated in albite indicate that the highest temperature is not more than 350 鈩，

本文編號：1464191